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Old 09-03-2022, 12:50 AM   #26
Kjets On a Plane
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Originally Posted by dl242gt View Post
No 240 turbos were sold in the UK as new. Which is funny because of the famous Volvo 245 turbo picture parked in front of Harrods in London.
No 240Turbos sold in any RHD country to my knowledge?
Fuel is expensive & UK was in decline, turbo doesn’t fit well around the steering shaft.

Give them the option of hotter N/a engines or R-sport tuning kit for their carbed 360s &/or 240GLTs &/or R-sport 16V head if they’ve really got money to burn (unlikely given the avg. UK Volvo driver (or Volvo driver, generally? ) & call it a day?

I’d think you’d want a line pressure regulator that references manifold pressure or vacuum, ultimately; regardless of WUR or CPR hackery that does that?
Some CI cars do that as well; makes sense; how do you keep the differential across the injectors constant (like the post-D-jet EFI models do), particularly with more boost?

The B21FT lambda flows about the same in absolute terms, but the step from lambda trimmed to fixed 50% duty cycle is often trimmed pretty lean to 3psi or a LOT more fuel above 3psi, especially if engine flows a lot better than the stock B21FT with a bit more static compression and shaved head & block.

All the 240Turbos in Europe were ridden hard and put away wet or getting fixed up back to original if the car is at all savable & fuel dist isn’t a ball of rust by now…

The dirtbag lowlife VW or Porsche 924 Crowd will have to take what they can get (lambda, KE or otherwise).
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Old 09-04-2022, 06:52 AM   #27
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UK in decline and fuel expensive? Sounds familiar! I'm surprised we still get cars at all.

When I tested on my 924, increasing line pressure from 5 bar to 6 bar did not result in any additional fuel at the injectors. This may be down to a low quality or failing fuel pump though. Next step is replacement of my fuel pump with a higher flowing item to verify that.

I am sure a Lambda fuel distributor will work. I can just run it as CIS-basic by replacing the frequency valve with a fixed restriction that allows the same flow through as the frequency valve would have at a fixed duty cycle. If B21FT is much more common than B21ET then that's probably the way to go but as you say this stuff is getting rare and the days of just going to a scrapyard and finding scrap 242T to steal the metering head from for your turbo Golf GTi are long gone. I think I'm the first to try it on a 924 though.

Is there a specification for the flow rate through the frequency valve at a given duty cycle? I will have to consider this when specifying a pump as not only do I have to feed the injectors but also the WUR return (220 cc/minute nominal) and the frequency valve return (can't find a flow rate figure).
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Old 09-04-2022, 03:39 PM   #28
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There was a place selling electronically controlled control pressure regulators. I think they were called unwired tools or something like that. I have a hoard of B21FT parts. Let me know if I can help. PM me.
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Old 09-06-2022, 10:03 AM   #29
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I found the rating for the frequency valve for a Porsche 911 is 240 cc per minute fully open. I imagine they are all fairly similar.

So assuming the worst-case 350 cc/injector fuel requirement I need, at 6 bar system pressure (no need to increase system pressure on Lambda style system, better to increase FV flow):
1400 cc for injectors
220 cc for WUR
240 cc for frequency valve at 100% duty cycle or equivalent
for a total of 1,860 cc per minute or 112 liters per hour.

This Pierburg pump is item (3) in the flow chart below and should flow around 155 liters per hour at 6 bar with an input voltage of 12V, it should be more than sufficient.


@dl242gt: Some people in 924 land were using UTCIS but I'd rather keep all electronics out of this build unless I absolutely have no choice. I'll contact you about B21FT stuff once I've replaced the fuel pump and measured my return and injector flows again.
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Old 09-14-2022, 04:31 PM   #30
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The 240Turbo is about your only/best choice HP/cylinder wise setup for 4-banger out of the box.

You can do something more like Grp-A cars so & use an 8cyl part with 2 ports feeding one larger injector, but it gets kludgy &/or costly fast…

I also have tested B21FT parts and 2 known good running 240Turbos to test them on with the Bosch injector tester for CI and diesel somewhere around here…

I’m sure you’d prefer B21ET non-lambda.

Idk what your fuel sender looks like? Our later ‘78+ fuel tanks with the Mikey mouse band-aid cheap AC-delco or VDO lift pumps kinda suck?
But for safety and emissions as a band-aid into a chassis designed in 1965 (140 as the 240 predecessor & cousin) it makes sense in its way?

Only USA market 240s came with the tank with the fume expansion chamber initially, but I think Europe got it too for ‘86+ 240 models…

The smart money used to be to install the pre 1977 tank with the brass filter and side spout gravity feed w/anti slosh bucket and old style 155lpr side spout style single pump or dual benz in series pumps when recombining the junk drawer?

With The 2 pump tank & lousy (compromised from the start?) sender setup we got 1977-1978+, it’s easy to stir the fuel too much and the Oe 240 lift pump kinda sucks (or doesn’t (suck fuel, maybe air & dirt?), that’s kinda part of the problem?)…some models came with a larger pickup sock filter and combined with a Porsche 930 or 740T lift up, us 240Turbo guys could keep the main roller cell pump from having to work unreasonably hard and give good service life in cooler climates parked in the shade (I’d say the UK was traditionally that, but it was what, ~101F in the SE of England snd some Scottish water reservoirs were running dangerously low?), but it’s still not great/ideal and there are always compromises when it comes to stirring the fuel unless you’re going to go full airplane and use a bladder/juice box for fuel with floating pickup and 1 line system with a surge tank that can be inverted &/or shaken every which-way under full load/power or no power or light cruise no problem…
…if you have to ask how much that costs…

Last edited by Kjets On a Plane; 09-14-2022 at 04:37 PM..
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Old 09-17-2022, 09:58 AM   #31
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WUR rises control pressure pretty quickly, i would say a couple minutes from cold autumn start and pressure is up.

I have dreamed of using Mega to control control pressure but never found time to test that idea. More duty cycle to frequency valve, more fuel.
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Old 09-19-2022, 03:38 PM   #32
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The 924 uses an in-tank sender pump and an external in-line high pressure pump.

The in-line pump used on the 924 is meant to be the same Bosch item used on the 911 up to and including the 3.0 SC with 210 hp but unfortunately with the state of 924 values the pumps will either be 40 years old and worn out, or replaced with the cheapest aftermarket part possible.

The same in-tank pump was used across Porsche's model range up to and including the 300hp 928S. After they switched to EFI for the 944, the in-tank pump was deleted and replaced by a simple strainer, no doubt due to the much lower fuel pressure requirement. The in-tank pump may be weak after 40 years so I will test its flow rate in isolation to ensure it can supply adequate flow to feed the main pump.

The fuel heating/stirring issue is why I went with the Pierburg pump instead of for example a Bosch 044 with double the flow rate. Better to have a comfortable margin and comfortable current draw than a huge margin with huge current draw.

I was originally planning on installing the new pump and doing the tests this weekend but had to push it back to the end of the month.
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Old 10-03-2022, 03:12 PM   #33
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Disaster: fuel pump replaced but I still have the same pathetic return flow volume!
The pump is working terribly hard and needed a 25 amp fuse just to not blow the fuse.
Blockage in my fuel lines I guess... this will be an annoying one to diagnose. Any thoughts?
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Old 10-04-2022, 09:51 AM   #34
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Clogged fuel strainer?
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Old 10-04-2022, 12:03 PM   #35
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Are the fuel inlet and outlet lines reversed on the fuel distributor?
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Old 10-05-2022, 06:08 AM   #36
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Fuel strainer in the tank is fine, the in-tank pump can put out 3500 ml/minute as I tested it.

The fuel filter is brand new.

The car runs well, I suspect it would not run at all if the inlet and outlet lines on the fuel distributor were reversed!

Can fuel accumulators fail internally and form a blockage? It's the only other part in the system I could describe as a "component" and not just a bit of tube.
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Old 10-05-2022, 11:38 AM   #37
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I've had several accumulators fail. Never a blockage but it could be possible if the insides ruptured and fell apart. Then it may block a port. They usually fail in the mode where they don't dampen the fuel pump pulses and warm starts take a bit of extra cranking and then the engine stutters till the pressure comes up.
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Old 11-13-2022, 08:57 AM   #38
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Really slow progress on this unfortunately.
I finally tested the fuel flow.

After the filter, before the metering head (no pressure): 3200cc per minute - 90% of spec
At the metering head return port (5.75 bar): 1300cc per minute - 50% of spec!!!

Two options then:
1. The pump is **** and doesn't conform to spec.
2. The voltage drop when the pressure is increased is monstrous and the pump runs very poorly.

I measured 12.8V at the battery, 12.1V at the fuse, and 10.2V at the pump with it running at 5.75 bar.
Next step will be to replace the fuel pump wiring with some thick cable like 8 or 6 AWG, either way it will be needed, whether to improve the flow from the current pump or to replace it with an Bosch 044 in the worst case.
The original wiring is metric and falls between 13 and 14 AWG. All the wiring on these cars is under specced...
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Old 11-15-2022, 05:38 PM   #39
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Theoretical question: comparing two cars where one runs lean, at 14 AFR, and one has a more suitable 12 AFR or even less, in the real world, how many more PSI would you be able to run on the 12 AFR car?
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Old 11-16-2022, 02:58 PM   #40
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Too many factors involved to give a good psi to afr levels. Maybe someone like Kenny who has dyno experience with seeing these kinds of changes. This is where your wideband should help as you will see in real time what will lean out the engine as you raise boost.
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Old 11-24-2022, 02:55 PM   #41
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I corroborated a flow of only 900 cc/minute on that Saab metering head I have so it does seem like it's insufficient for what I want to do and not just a bad unit. A pity, but at least I've done the plumbing and proved that you can fit a 6-cylinder metering head on 924 without a terrible amount of difficulty.

Next steps will be to rewire the fuel pump, and then to get a B21FT metering head - I'll use the (no longer needed) return to tank from the Hot Start Solenoid (which I deleted) as the return flow for the "frequency valve" which will actually be a manually adjustable needle valve with a fixed flow rate (essentially equivalent to a fixed duty cycle FV).

Certainly a 2023 project though. It's going to be too cold to work on cars for the next few months.
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